The present invention relates to a revolving armature for rotary electric machinery in which insulator-coated coils are wound in multiple layers, and more particularly to a revolving armature for rotary electric machinery which has a structure for maintaining an insulation distance between upper and lower coils near a riser of a commutator where insulator-coated coils are connected to the commutator.
A conventional revolving armature for rotary electric machinery is structured such that insulator-coated coils are wound in slots of a magnetic (iron) core in multiple layers and parts of the coils where insulator coatings are peeled off are electrically connected to a commutator conductor, i.e., its riser for coil connection. Such a known revolving armature for rotary electric machinery is described in, e.g., JP, A, 63-11045 and JP, A, 63-265550.
Heretofore, to electrically connect insulator-coated coils to the riser for coil connection, it has been required to peel off insulator coatings from distal ends of the insulator-coated coils beforehand. At this time, because of relatively large variations in the peeling work, adjacent portions of the insulator coatings which are located near the coil distal ends but out of the riser may be also peeled off excessively, in addition to contact portions thereof which are directly contacted with the riser. Accordingly, when the insulator-coated coils are wound in multiple layers, there is a possibility that an insulator peeled-off portion of an upper coil and an insulator peeled-off portion of a lower coil may cross each other and cause a short-circuit between the upper and lower coils.
For that reason, an interlayer insulating sheet is generally disposed between the upper and lower coils.
The above-stated prior art has had the problem that a work step of providing an interlayer insulating sheet between the upper and lower coils is necessary and the productivity of revolving armatures is poor.
An object of the present invention is to provide a revolving armature for rotary electric machinery which can be produced with high efficiency.
To achieve the above object, the present invention provides a revolving armature for rotary electric machinery comprising a magnetic core fixed to a shaft and having a plurality of slots formed in an outer periphery thereof, a plurality of insulator-coated coils wound in the slots of the magnetic core in multiple layers, and a commutator fixed to the shaft and provided with conductors including risers for connection to the insulator-coated coils, wherein end portions of the insulator-coated coils include at least contact portions deprived of insulator coatings and connected to the risers, and adjacent portions next to the contact portions but out of the risers, and a stepped portion is formed in at least one of the adjacent portion of an upper coil and the adjacent portion of a lower coil of the insulator-coated coils wound in multiple layers at a location where the upper coil and the lower coil face each other in crossing relation. With this arrangement, a sufficient insulation distance between the upper and lower coils is ensured at the location where the coils are crossing each other, an insulating member such as an interlayer insulating sheet is no longer needed, and the productivity of revolving armatures for rotary electric machinery is improved.
In the above revolving armature for rotary electric machinery, the stepped portion is preferably formed in both the adjacent portion of the upper coil and the adjacent portion of the lower coil at the location where the upper coil and the lower coil face each other. With this arrangement, a sufficient insulation distance between the upper and lower coils is ensured at the location where the coils are crossing each other, and an insulation failure is prevented.
In the above revolving armature for rotary electric machinery, the stepped portion formed in the adjacent portion and a peeled-off portion in the contact portion where the insulator coating is removed are preferably formed by pressing using a punching die.
In the above revolving armature for rotary electric machinery, when the stepped portion is preferably formed, the corresponding coil is cut in an amount not larger than that by which the coil is cut in the contact portion to deprive of the insulator coating for forming a peeled-off portion so that the coil has a cross-sectional area in the stepped portion not less than that in the contact portion. With this arrangement, in spite of forming the stepped portion in the coil, design of the rotary electric machinery is affected in no way by the formation of the stepped portion.